OpenGL is a graphics standard and API which targets the desktop and workstation markets. It is designed to be easy to accelerate with dedicated computer hardware, and hence most implementations give greatly improved performance over traditional software rendering. Currently, OpenGL is used for ...

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4answers
3k views

Generating triangles from a square grid

I have a 2D square grid of values representing terrain elevations, and I want to generate triangles from that grid to make a 3D view of the terrain. My first thought was to split each square ...
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votes
2answers
5k views

Toggle Fullscreen at Runtime

Using the library GLFW, I can create a fullscreen window using this line of code. glfwOpenWindow(Width, Height, 8, 8, 8, 8, 24, 0, GLFW_FULLSCREEN); The line for creating a standard window looks ...
6
votes
1answer
382 views

Why would I support multiple rendering engines simultaneously?

I've seen some games from the early 2000s that had a launcher where you could select the rendering engine you wanted to use: DirectX or OpenGL. Maybe I haven't looked hard enough, but I haven't seen ...
6
votes
2answers
597 views

GL_EXT_draw_instanced vs VBO's

I'm having trouble understanding the benefit of the newer GL_EXT_draw_instanced over traditional VBO's. Don't both keep geometry cached on the gpu for faster redrawing? VBO's seem much more ...
6
votes
1answer
7k views

How to use modern OpenGL for 2D games?

I've found a plethora of "modern" OpenGL (3.0+) tutorials for 3D, but I have found next to nothing when looking for information on how to use it for 2D game development. How can I get started using ...
6
votes
2answers
941 views

Best way to do buttons for an OpenGL ES iPhone game

I'm making a simple 2d game in OpenGL ES and I want to add movement buttons to it. What's the best way of going about this? In previous projects I've simply added UIButtons to the view but I hear ...
6
votes
1answer
464 views

Display Lists in OpenGL

I heard that there was a faster method of displaying vertices, rather than recreating the GL_TRIANGLES, each time the scene is drawn. I thought I read somewhere that this method was obselete. Why ...
6
votes
2answers
1k views

Fixed Function vs Programmable Pipeline performance with many batches

In OpenGL 2.0 I can easily make 10,000 draw calls per frame (with state changes in between each call). However, if i try to do this in either OpenGL ES 2.0 or DirectX9 with shaders, my peformance is ...
6
votes
1answer
1k views

Efficiently rendering to 3D texture

I have an existing depth texture and some other color textures, and want to process the information in them by rendering to a 3D texture (based on the depth contained in the depth texture, i.e. a ...
6
votes
1answer
256 views

Get SFML to report the version of OpenGL that is being used

How can I get SFML to report the version of OpenGL that is being used by the render window?
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votes
2answers
560 views

Should I batch up debug primitives for rendering in modern OpenGL?

I've recently started porting some old rendering demos I did to modern OpenGL. I had a debug drawing class in my old code which used immediate mode glBegin(), glEnd() etc. for rendering debug objects ...
6
votes
3answers
2k views

Direct3D and OpenGL Matrix representation

As I read in OpenGL matrices are column major. It means that if I create a 16 element array first four elements are the first column in matrix. Is it the same for Direct3D or any transformation's ...
6
votes
4answers
11k views

Wavefront *.obj loader in C++

I'm creating a game using OpenGL (via SDL) and C++ (via Visual Studios 2010 Professional). During the game, I will be using 3D character animation. I'd like to use wavefront *.obj files for all the 3D ...
6
votes
1answer
5k views

Help understanding gluLookAt()

I am fairly new to openGL( 3 months ) and am asking for assistance in understanding the fundamentals behind gluLookAt(). Currently I have spent most of my time with openGL modeling scenes with fixed ...
6
votes
1answer
1k views

VBO and gl*Pointer management practises?

I'm aware it's not a simple yes/no question and for the moment I can't tell if it can be simply answered, or is it a topic for a long discussion which is not suitable for our Q&A format. I want ...
6
votes
1answer
691 views

GLSL subroutine not being used

I'm using a gaussian blur fragment shader. In it, I thought it would be concise to include 2 subroutines: one for selecting the horizontal texture coordinate offsets, and another for the vertical ...
6
votes
2answers
975 views

How are dynamic blending shadows like this created?

I would like to know, how dynamic shadows, that 'blend' onto other objects, are created.
6
votes
1answer
1k views

Rendering 2D grass

My current project, using Java and OpenGL, has a fairly standard overhead tilemap in the style of the Zelda games. I'd really like to add "real" grass to the grass tiles so that there are actually ...
6
votes
2answers
361 views

Changing player color without multiple player bitmaps [duplicate]

Possible Duplicate: How to colorize certain parts of a model - like RTS games have those team colors? Ok, so here is my current situation. I have a player model, fully UV mapped, and ...
6
votes
1answer
712 views

Sprite with alpha Blending in 3D world

I'm working on a game in a 3D world with elements 2D only (Like Don't starve game) for Android and IOS. Currently, I've managed "Sprite" without alpha blending, I've just put a condition in the pixel ...
6
votes
1answer
5k views

GLSL - Rewriting shaders from #330 to #130

I recently created a game (LD21) that uses a geometry shader to convert points into textured triangles/culling. Since I was under the impression that the support for #330 was widespread I only wrote ...
6
votes
1answer
352 views

With what projection matrix should I render a portal to a texture?

I'm using OpenGL. I have problem with my engine's portal implementation. To create the first portal I do: create a virtual camera with the position of the second portal and the correct orientation ...
6
votes
1answer
2k views

Exponential Variance Shadow Mapping - implementation

I use a variance shadow mapping with a "standard" light bleeding fix in my graphics engine which is based on deferred rendering.. I have a single shadow map for a directional light beacause a test ...
6
votes
1answer
1k views

Octree implementation for fustrum culling

I'm learning modern (>=3.1) OpenGL by coding a 3D turn based strategy game, using C++. The maps are composed of 100x90 3D hexagon tiles that range from 50 to 600 tris (20 different types) + any ...
6
votes
2answers
639 views

An odd performance problem rendering a simple scene (less than 14k vertices) in OpenGL using two vbos with LWJGL

Problem I have been having a strange degrading performance issue rendering a simple scene containing two "chunks" of 4x4x4 cubes each. Video of problem This is a screen capture showing my console ...
6
votes
1answer
5k views

Making a camera in a 2D game (glOrtho)

I'm trying to make a camera that follows my character and it seems I've managed. However, I don't know how to limit that my camera don't follow me when my character reachs the boundaries of the ...
6
votes
2answers
774 views

Textures for an underwater environment?

I'm trying to build an underwater scene. I'm including my scene in a large cube, which I'm going to texture with images that resemble an underwater environment. Where can I get textures for something ...
6
votes
3answers
1k views

How can I get into opensource game development? [closed]

The short and sweet question I'm new to game programming in general, so how do I go about making GOOD QUALITY opensource games? What I have come across There are a multitude of games that I have ...
6
votes
1answer
669 views

Texture coordinate discontinuity with mipmaps creates seams

I just started learning openGL and I am getting this artifact when texturing a sphere with mipmaps. Basically when the fragment samples the edge of my texture, it detects the discontinuity (say from 1 ...
6
votes
2answers
3k views

Using a GLSL fragment shader to draw a texture in the middle of a quad

I'm not sure how possible this is, but I'm trying to use a fragment shader to draw a portion of a texture in the middle of a quad. This is all 2D. The quads consist of four vertices from (0, 0) to ...
6
votes
1answer
2k views

How to manage shaders?

I've done some shader programming some time ago but only simple stuff. I'm especially interested in how do you manage shaders? Do you just write one of each kind, or do you need more of them? If so, ...
6
votes
1answer
956 views

Vertex data split into separate buffers or one one structure?

Is it better to have all vertex data in one structure like this: class MyVertex { int x,y,z; int u,v; int normalx, normaly, normalz; } Or to have each component ...
6
votes
1answer
3k views

Using glReadBuffer/glReadPixels returns black image instead of the actual image only on Intel cards

I have this piece of code glReadBuffer( GL_FRONT ); glReadPixels( 0, 0, width, height, GL_RGB, GL_UNSIGNED_BYTE, buffer ); Which works just perfectly in all the Nvidia and AMD GPUs I have tried, ...
6
votes
1answer
2k views

Weird error with opengl in Android using Libgdx : “EGL_BAD_ATTRIBUTE”

I am having a weird error when uploading my game in the phones. E/Adreno200-EGL(5128): qeglDrvAPI_eglGetConfigAttrib:484>: EGL_BAD_ATTRIBUTE I am uploading the textures with AssetManager. I am ...
6
votes
1answer
177 views

Excluding Background from Color Picking

I've implemented picking based on color coding, but I don't want the background color to be pickable. Is there any way in openGL (2.x) to exclude the background color? For some reason, doing ...
6
votes
1answer
998 views

OpenGL ES object rotation around z axis

I have an object on my screen which is presented rotated and panned, But i have 2 problems regarding the z axis rotations. It's a bit tricky to explain so i uploaded 2 videos to describe each problem. ...
6
votes
1answer
347 views

How to debug framerate drops with VBOs, OpenGL

I'm working on an experimental app to test how VBOs perform when rendering a minecraft-like world. If the performance is better than what I use now I'll update my actual game. Based on what everyone ...
6
votes
2answers
989 views

Atmospheric scattering and sky geometry

I'm trying to implement an atmospheric scattering in my graphics (game) engine based on the GPU Gems article: link. An example implementation from that article uses a skydome. My scene is different - ...
6
votes
3answers
783 views

State of the art Culling and Batching techniques in rendering [closed]

I'm currently working with upgrading and restructuring an OpenGL render engine. The engine is used for visualising large scenes of architectural data (buildings with interior), and the amount of ...
6
votes
1answer
367 views

How to find the bottleneck in a typical OpenGL game?

I am working on a little game engine. All major features are implemented yet, despite game logic which I assume not to be such a computational effort. The framerate is at least around 40 FPS, most of ...
6
votes
1answer
428 views

Weird problem with advect program in fluid simulator

I implemented 2d fluid simulator. Solver runs entirely on GPU. All works fine... on my work PC. But on home PC I have some awful glitches, and I can`t understand how to fix them. Empirically I ...
6
votes
2answers
2k views

Getting the number of fragments which passed the depth test

In "modern" environments, the "NV Occlusion Query" extension provides a method to get the number of fragments which passed the depth test. However, on the iPad / iPhone using OpenGL ES, the extension ...
6
votes
1answer
1k views

How can I get my meshes to work with Bullet Physics?

The problem is that I'm trying to use my meshes with Bullet Physics for the collision part of my game. When I attempted doing this method with my GLM(model loading library by nate robins) model, I ...
6
votes
1answer
3k views

gl_PointCoord always zero

I am trying to draw point sprites in OpenGL with a shader but gl_PointCoord is always zero. Here is my code Setup: //Shader creation..(includes glBindAttribLocation(program, ATTRIB_P, "p");) ...
6
votes
1answer
2k views

Atmospheric Scattering

I'm trying to implement atmospheric scattering based on Sean O`Neil algorithm that was published in GPU Gems 2. But I have some trouble getting the shader to work. My latest attempts resulted in: ...
6
votes
3answers
1k views

Common light map practices

My scene consists of individual meshes. At the moment each mesh has its associated light map texture, I was able to implement the light mapping using these many small textures. 1) Of course, I want ...
6
votes
0answers
218 views

OpenGL profiling with AMD PerfStudio 2 [closed]

I'm rendering just a really small amount of polygons for my UI but however I still tried to increase the FPS. In the end I removed redundant calls which increased the FPS. I really don't want to lose ...
6
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0answers
2k views

OpenGL problem with FBO integer texture and color attachment [closed]

In my simple renderer, I have 2 FBOs one that contains diffuse, normals, instance ID and depth in that order and one that I use store the ssao result. The textures I use for the first FBO are RGB8, ...
6
votes
1answer
268 views

Why does accessing a uniform float make my shader more than twice as slow?

My fragment shader was significantly slowed down by a recent change, and I've been trying to understand why. I isolated the main slow-down to accessing a single particular uniform float. If I include ...
6
votes
1answer
348 views

Getting started to OpenGL - little question

Im starting to learn opengl, and after 2 days, searching and trying hard, i finally installed all the libraries i need (lol). So, I'm following this tutorial, and it says to use glfwOpenWindowHint ...